Oil upgrading within combustion exhaust

ABSTRACT

Methods and systems relate to upgrading hydrocarbons, such as bitumen, by contacting the bitumen with flue gas of oxy-combustion. Quenching a mixture formed of the bitumen and the flue gas controls conversion of the bitumen. Limited size and amount of equipment needed enables employing such upgrading at production fields to facilitate making the bitumen transportable by pipeline without relying on diluents.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application which claims benefit under 35 USC §119(e) to U.S. Provisional Application Ser. No. 61/752,136 filed Jan. 14, 2013, entitled “OIL UPGRADING WITHIN COMBUSTION EXHAUST,” which is incorporated herein in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None.

FIELD OF THE INVENTION

Embodiments of the invention relate to systems and methods of upgrading hydrocarbons by direct contact with combustion products.

BACKGROUND OF THE INVENTION

High viscosity of heavy oil or bitumen makes transportation from a production location to a refinery for processing a challenge and economic factor in recovering such resources. In one prior approach, adding diluents, such as natural gas condensate or naphtha, to the bitumen reduces the viscosity enough to enable pipeline transport of a resulting mixture known as dilbit. Expense of the diluents along with their transportation costs, however, adds to operating costs.

Further, refining the diluents with the bitumen means that feed run through the refinery contains hydrocarbons having low and high molecular weights but limited mid-range molecular weights. Use of the diluents may thus limit value and marketability depending upon processing capabilities and requirements of the refinery. Regardless of the diluents, upgrading the bitumen in the refinery can also limit its conversion capacity.

Some producers therefore eliminated need for the diluents by upgrading the bitumen into synthetic crude before transporting to the refinery. Such upgrading, however, requires multiple processing units including distillation columns, cokers, hydrogen facilities, and hydrotreaters. These processing units can amount to onsite refining and are, hence, capital intensive.

Therefore, a need exists for systems and methods of upgrading the bitumen that are cost efficient and result in products to facilitate transporting by pipeline and conversion in refineries.

BRIEF SUMMARY OF THE DISCLOSURE

In one embodiment, a method of upgrading hydrocarbons includes combusting oxygen and fuel inside a vessel to generate flue gas and introducing the hydrocarbons into the vessel in contact with the flue gas to cause thermal cracking of the hydrocarbons. Quenching a mixture of the hydrocarbons and the flue gas controls conversion of the hydrocarbons. The method further includes separating the mixture into an aqueous stream, a gaseous stream and a products stream containing the hydrocarbons that have been upgraded.

For one embodiment, a system for upgrading hydrocarbons includes a vessel coupled to receive oxygen and fuel for combustion inside the vessel to generate flue gas. The vessel includes a first inlet to introduce the hydrocarbons into the vessel in contact with the flue gas for thermal cracking of the hydrocarbons and a second inlet to introduce a coolant for controlling conversion of the hydrocarbons by quenching a mixture of the hydrocarbons and the flue gas. The system further includes a separator coupled to receive the mixture for splitting into an aqueous output, a gaseous output and a product output containing the hydrocarbons that have been upgraded.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and benefits thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings.

FIG. 1 is a schematic of a system for upgrading bitumen in presence of oxy-combustion with subsequent quench and product separation, according to one embodiment of the invention.

FIG. 2 is a schematic of a system for upgrading bitumen recycled for multiple introductions into a vessel of the oxy-combustion in order to enhance the upgrading, according to one embodiment of the invention.

FIG. 3 is a schematic of a system for upgrading bitumen with the oxy-combustion cooled by recycling flue gases, according to one embodiment of the invention.

DETAILED DESCRIPTION

Turning now to the detailed description of the preferred arrangement or arrangements of the present invention, it should be understood that the inventive features and concepts may be manifested in other arrangements and that the scope of the invention is not limited to the embodiments described or illustrated. The scope of the invention is intended only to be limited by the scope of the claims that follow.

Embodiments of the invention relate to systems and methods of upgrading hydrocarbons, such as bitumen, by contacting the bitumen with flue gas of oxy-combustion. Quenching a mixture formed of the bitumen and the flue gas controls conversion of the bitumen. Limited size and amount of equipment needed enables employing such upgrading at production fields to facilitate making the bitumen transportable by pipeline without relying on diluents.

FIG. 1 shows a system for upgrading bitumen that includes an air separation unit (ASU) 100, a pump or compressor 102, a reactor vessel 104 and a separator 106. In operation, the ASU 100 separates nitrogen and other air constituents from an oxygen output that is rich in oxygen (e.g., at least 90% or 95% oxygen by weight) relative to the air. The oxygen output couples to the pump or compressor 102 that pressurizes the oxygen supplied to the reactor vessel 104. In some embodiments, liquid oxygen is pumped to such desired pressure before heat exchange to vaporize in order to limit costs for compression.

The oxygen and fuel, such as natural gas or methane, ignite inside the vessel 104 operated at a pressure above ambient and suitable for thermal cracking conditions (e.g., above 5 bar or between 5 and 15 bar). In some embodiments, the vessel 104 design derives from a direct steam generator (or DSG) in which water vaporizes upon direct contact with combustion products. A fluid, such as water, introduced through an inlet into the vessel 104 upstream or ahead of an inlet for the bitumen into the vessel 104 controls internal temperatures for ensuring thermal integrity of components and providing the desired thermal cracking conditions (e.g., between 400° C. and 540° C.). Vaporization of the water whenever introduced into the vessel 104 may contribute to the cooling within the vessel 104.

The bitumen then enters the vessel 104 and contacts flue gas from combustion of the fuel with the oxygen. Rapid heating of the bitumen provided in the vessel 104 favors cracking reactions and thus reduces yield losses to coking products. Hydrogen and/or steam from the water introduced and/or the combustion products further reduce coke formation. The hydrogen content comes from the combustion and can be influenced by operating parameters. In some embodiments, the hydrogen may be generated by steam methane reforming for use as the fuel and supplied in excess of the oxygen. The hydrogen in flue gas also limits olefin formation as desired.

An inlet into the vessel 104 downstream of where the bitumen enters the vessel 104 introduces a coolant, such as water, to quench the cracking reactions of the bitumen at a desired conversion point. An effluent mixture from the vessel 104 thus contains the flue gas, water/steam, and upgraded products and is passed to the separator 106. The separator 106 divides the mixture based on phases into a gaseous stream, an aqueous stream and a products stream that flow through respective outputs of the separator 106.

The gaseous stream contains the flue gases including carbon dioxide from the oxy-combustion. Further gas treatment may provide for cost efficient capture of the carbon dioxide given limited nitrogen content as a result of using the ASU 100. The gaseous stream further contains light hydrocarbons resulting from the cracking of the bitumen.

The aqueous stream contains the water from the oxy-combustion and injections to reduce temperatures in the vessel 104. Solid coke material caused by the heating of the bitumen may partition with the aqueous stream such that solids are withdrawn from the products stream as desired for pipeline transport thereof. Filtering and treatment of the aqueous stream may allow for its reuse, such as recycling of the water back to the vessel 104.

The products stream contains the hydrocarbons that are liquid and have been upgraded by the thermal cracking to enable transporting the products stream by pipeline from a production field where the vessel 104 is located to a remote refinery for additional processing. In some embodiments, the bitumen enters the vessel 104 having an American Petroleum Institute (API) gravity less than 15° while the products stream exits the separator 106 having an API gravity greater than 19°. The products stream may thereby meet pipeline specifications without relying on diluents.

FIG. 2 illustrates the system shown in FIG. 1 with addition of a recycle loop for the effluent mixture from the vessel 104. Part of the effluent mixture thus reenters the vessel 104 for multiple passes of the bitumen through where the thermal cracking occurs. This recycle enhances the upgrading in some embodiments to achieve higher conversions.

FIG. 3 shows the system depicted in FIG. 1 but further including a recycle loop for the fluid input into the vessel 104 in order to control temperatures before addition of the bitumen. Part of the flue gas withdrawn from the vessel 104 passes through a heat exchanger 300 and is hence cooled before being purged with a remainder reintroduced into the vessel 104. This recycling of the flue gas promotes overall energy efficiency of the system since energy required to vaporize the water is not lost but rather exchanged with other facility energy needs.

In closing, it should be noted that the discussion of any reference is not an admission that it is prior art to the present invention, especially any reference that may have a publication date after the priority date of this application. At the same time, each and every claim below is hereby incorporated into this detailed description or specification as additional embodiments of the present invention.

Although the systems and processes described herein have been described in detail, it should be understood that various changes, substitutions, and alterations can be made without departing from the spirit and scope of the invention as defined by the following claims. Those skilled in the art may be able to study the preferred embodiments and identify other ways to practice the invention that are not exactly as described herein. It is the intent of the inventors that variations and equivalents of the invention are within the scope of the claims while the description, abstract and drawings are not to be used to limit the scope of the invention. The invention is specifically intended to be as broad as the claims below and their equivalents. 

1. A method of upgrading hydrocarbons, comprising: combusting oxygen and fuel inside a vessel to generate flue gas; introducing the hydrocarbons into the vessel and in contact with the flue gas to cause thermal cracking of the hydrocarbons; quenching a mixture of the hydrocarbons and the flue gas to control conversion of the hydrocarbons; and separating the mixture into an aqueous stream, a gaseous stream and a products stream containing the hydrocarbons that have been upgraded.
 2. The method according to claim 1, wherein the quenching includes introducing water into the mixture for vaporization.
 3. The method according to claim 1, wherein the flue gas contains hydrogen and steam to limit coking and olefin formation.
 4. The method according to claim 1, further comprising separating the oxygen from air prior to supplying the oxygen to the vessel.
 5. The method according to claim 1, further comprising cooling the flue gas prior to introducing the hydrocarbons into the vessel.
 6. The method according to claim 1, further comprising cooling the flue gas with water prior to introducing the hydrocarbons into the vessel.
 7. The method according to claim 1, further comprising cooling the flue gas by passing a portion of the flue gas through a heat exchanger before being recycled and combined with a remainder of the flue gas prior to introducing the hydrocarbons into the vessel.
 8. The method according to claim 1, wherein the vessel is located in a production field to provide the upgrading remote from a refinery.
 9. The method according to claim 1, further comprising transporting the products stream by pipeline to a refinery for additional processing.
 10. The method according to claim 1, wherein the hydrocarbons include bitumen and the products stream meets pipeline specifications without relying on diluents.
 11. The method according to claim 1, wherein the hydrocarbons when introduced into the vessel have an American Petroleum Institute (API) gravity less than 15° and the products stream has an API gravity greater than 19°.
 12. The method according to claim 1, further comprising withdrawing solid coke material with the aqueous stream from the products stream.
 13. A system for upgrading hydrocarbons, comprising: a vessel coupled to receive oxygen and fuel for combustion inside the vessel to generate flue gas, wherein the vessel includes a first inlet to introduce the hydrocarbons into the vessel and in contact with the flue gas for thermal cracking of the hydrocarbons and a second inlet to introduce a coolant for controlling conversion of the hydrocarbons by quenching a mixture of the hydrocarbons and the flue gas; and a separator coupled to receive the mixture for splitting into an aqueous output, a gaseous output and a product output containing the hydrocarbons that have been upgraded.
 14. The system according to claim 13, wherein the coolant is water introduced into the mixture for vaporization.
 15. The system according to claim 13, wherein the flue gas contains hydrogen and steam to limit coking and olefin formation.
 16. The system according to claim 13, further comprising a third inlet into the vessel disposed to introduce a fluid for cooling the flue gas ahead of the first inlet for introducing the hydrocarbons into the vessel.
 17. The system according to claim 13, further comprising a third inlet into the vessel disposed to introduce water for cooling the flue gas ahead of the first inlet for introducing the hydrocarbons into the vessel.
 18. The system according to claim 13, further comprising a recycle loop off of the vessel and including a heat exchanger for cooling at least some of the flue gas ahead of the first inlet for introducing the hydrocarbons into the vessel.
 19. The system according to claim 13, further comprising an air separation unit coupled to supply the oxygen to the vessel.
 20. The system according to claim 13, wherein the vessel is located in a production field to provide the upgrading remote from a refinery. 